The proposed studies will extend ongoing investigations of the potential, as human allergens, of a variety of airborne biological particles of demonstrated abundance. Specifically, spores of select ascomycetes, basidiomycetes and myxomycetes will be obtained from field sources or, rarely, laboratory culture and extracted to provide material for skin and mucosal testing of selected atopic subjects. Comparative allergenic properties of distinct "form species" of imperfect fungi will be assayed similarly and studied by the use of immunoadsorbents. Optimal methods for preparation of fungus extracts for clinical use will be sought and media for recovery of fungi from air compared critically. Present studies of the fungus flora of homes will be extended to survey possible actinomycete contamination and the role of humidifying equipment as a dominant source of microbial aerosols will be evaluated. Window air conditioning units will be studied, both as a means of excluding extramural aeroallergens and as a potential source of these agents. The possble occurrence of pollen allergens in association with aerosol fractions below 10 micra in equivalent diameter will also be sought.